Resonator element, resonator, resonator device, oscillator, electronic apparatus, and moving object

ABSTRACT

A resonator element includes a quartz crystal substrate in which a plane including X and Z′ axes is set as a main plane and a direction oriented along a Y′ axis is a thickness direction. The quartz crystal substrate includes a first region in which thickness shear vibration is generated, a second region that has a thickness thinner than the first region, and first protrusions that are disposed between one pair of electrode pads disposed to be lined in a direction oriented along a Z′ axis on a mounted side of the second region. When Lx is a length of the first protrusions along the X axis and λ is a wavelength of flexural vibration of the quartz crystal substrate, a relation of “λ/2×(2n+1)−0.1λ≦Lx≦λ/2×(2n+1)+0.1λ” (where n is a positive integer) is satisfied.

BACKGROUND

1. Technical Field

The present invention relates to a resonator element, a resonator, aresonator device, an oscillator, an electronic apparatus, and a movingobject.

2. Related Art

In the related art, there are known resonator elements using quartzcrystal. Such resonator elements are widely used as reference frequencysources, oscillation sources, or the like of various electronicapparatuses since frequency-temperature characteristics are excellent.In particular, since the frequency-temperature characteristics ofresonator elements using quartz crystal substrates cut at cut anglescalled AT-cut show cubic curves, the resonator elements are widely usedin mobile communication apparatuses such as mobile phones.

For example, JP-A-2012-114496 and JP-A-2012-114495 disclose AT-cutquartz crystal resonator elements which have multistage mesa structuresand in which vibration sections which are mesa sections include firstportions and second portions having thicknesses thinner than the firstportions and integrated in the circumferences of the first portions in aplan view. Here, when Z is the size of an AT-cut substrate in a Z′ axis,Mz is the size of the vibration section in the Z′ axis, and t is thethickness of the first portion of the vibration section and relations of“8≦Z/t≦11” and “0.6≦Mz/Z≦0.8” are satisfied, it is possible to reducethe value of equivalent series resistance, so-called crystal impedance(CI).

JP-A-2012-191300 and JP-A-2012-191299 disclose AT-cut quartz crystalresonator elements having multistage mesa structures. Here, by formingprotrusions on free end sides, a package and an excitation electrodeformed in the vibration section are prevented from coming into contactwith each other at the time of mounting on the package.

JP-A-2011-97183 discloses an AT-cut quartz crystal resonator elementhaving a multistage mesa structure. Here, by forming protrusions so thata vibration section is interposed between the protrusions, flexuralvibration is prevented.

In the foregoing resonator elements, however, when protrusions areformed at positions at which vibration displacement energy in thevibration sections is not sufficiently attenuated, vibrations ofexcitation portions are affected, and thus electric characteristics ofthe resonator elements may deteriorate in some cases.

SUMMARY

An advantage of some aspects of the invention is to provide a resonatorelement capable of reducing deterioration in electric characteristics.Another advantage of some aspects of the invention is to provide aresonator, a resonator device, an oscillator, an electronic apparatus,and a moving object including the resonator element.

The invention can be implemented as the following forms or applicationexamples.

Application Example 1

A resonator element according to this application example includes: aquartz crystal substrate in which an X axis of an orthogonal coordinatesystem having the X axis serving as an electric axis, the Y axis servingas a mechanical axis, and the Z axis serving as an optical axis, whichare crystallographic axes of quartz crystal, is set as a rotation axis,an axis inclined from the Z axis so that a +Z side is rotated in a −Ydirection of the Y axis is set as a Z′ axis, an axis inclined from the Yaxis so that a +Y side is rotated in a +Z direction of the Z axis is setas a Y′ axis, a plane including the X and Z′ axes is set as a mainplane, and the direction oriented along the Y′ axis is set as athickness direction; and a pair of electrode pads. The quartz crystalsubstrate includes a first region in which thickness shear vibration isgenerated, a second region that is located in periphery of the firstregion and has a thickness thinner than the first region, and a firstprotrusion that is disposed to be lined with the first region in adirection oriented along the X axis at one end side of the second regionalong the X axis. The one pair of electrode pads are disposed to belined in a direction oriented along the Z′ axis at the one end side ofthe second region in the direction oriented along the X axis. The firstprotrusion is present between the one pair of electrode pads. When Lx isa length of the first protrusion along the X axis and λ is a wavelengthof flexural vibration generated in the quartz crystal substrate, arelation of “λ/2×(2n+1)−0.1λ≦Lx≦λ/2×(2n+1)+0.1λ” (where n is a positiveinteger) is satisfied.

In the resonator element, a distance between the first protrusion andthe first region can be lengthened more than when the first protrusionis not formed between the electrode pads. Therefore, the firstprotrusion can be disposed in a region which vibration displacementenergy of thickness shear vibration by the first region does not reach.Accordingly, in the resonator element, it is possible to reduce theinfluence of the first protrusion on the vibration of the first region.As a result, it is possible to reduce deterioration in electriccharacteristics.

Application Example 2

In the resonator element according to the application example, when Lzis a length of the first protrusion along the Z′ axis and Mz is a lengthof the first region along the Z′ axis, a relation of “0<Lz/Mz≦0.7” maybe satisfied.

In the resonator element, it is possible to reduce equivalent seriesresistance.

Application Example 3

In the resonator element according to the application example, the firstprotrusion may be disposed in a region which vibration displacementenergy by the vibration section does not reach.

In the resonator element, it is possible to reduce the influence of thefirst protrusion on the vibration of the first region, and thus it ispossible to reduce the deterioration in the electric characteristics.

Application Example 4

In the resonator element according to the application example, the firstprotrusion may have two side surfaces extending along the Z′ axis. Ofthe two side surfaces, one side surface may be disposed at a position ofone maximum amplitude of the flexural vibration and the other sidesurface may be disposed at a position of the other maximum amplitude ofthe flexural vibration.

In the resonator element, it is possible to attenuate the thicknessshear vibration in the peripheral section while reducing the flexuralvibration, and thus it is possible to efficiently trap the vibrationdisplacement energy of the thickness shear vibration.

Application Example 5

The resonator element according to the application example may furtherinclude a pair of second protrusions that are disposed to be lined inthe direction oriented along the Z′ axis at the other end side of thesecond region along the X axis.

In the resonator element, it is possible to reduce the deterioration inthe electric characteristics of the resonator element, and it ispossible to reduce a possibility of the first region colliding against,for example, the package on which the resonator element is mounted anddamaging.

Application Example 6

In the resonator element according to the application example, the firstregion may include a first portion and a second portion that has athickness thinner than the first portion and is present between thefirst portion and the second region at least in a vibration direction ofthe thickness shear vibration in a plan view.

In the resonator element, it is possible to reduce the deterioration inthe electric characteristics of the resonator element, and it ispossible to realize an energy trapped effect of the thickness shearvibration in the first region.

Application Example 7

The resonator element according to the application example may furtherinclude excitation electrodes that are formed in the first and secondregions.

In the resonator element, it is possible to excite the quartz crystalsubstrate by the excitation electrode.

Application Example 8

A resonator according to this application example includes the resonatorelement according to the application example and a package in which theresonator element is accommodated.

Since the resonator includes the resonator element according to theapplication example, it is possible to reduce the deterioration in theelectric characteristics.

Application Example 9

A resonator device according to this application example includes: theresonator element according to the application example; and anelectronic element.

Since the resonator device includes the resonator element according tothe application example, it is possible to reduce the deterioration inthe electric characteristics.

Application Example 10

In the resonator device according to the application example, theelectronic element may be a thermosensitive element.

Since the resonator device includes the resonator element according tothe application example, it is possible to reduce the deterioration inthe electric characteristics.

Application Example 11

An oscillator according to this application example includes: theresonator element according to the application example; and anoscillation circuit that is electrically connected to the resonatorelement.

Since the oscillator includes the resonator element according to theapplication example, it is possible to reduce the deterioration in theelectric characteristics.

Application Example 12

An electronic apparatus according to this application example includesthe resonator element according to the application example.

Since the electronic apparatus includes the resonator element accordingto the application example, it is possible to reduce the deteriorationin the electric characteristics.

Application Example 13

A moving object according to this application example includes theresonator element according to the application example.

Since the moving object includes the resonator element according to theapplication example, it is possible to reduce the deterioration in theelectric characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a perspective view schematically illustrating a resonatorelement according to an embodiment.

FIG. 2 is a plan view schematically illustrating the resonator elementaccording to the embodiment.

FIG. 3 is a sectional view schematically illustrating the resonatorelement according to the embodiment.

FIG. 4 is a sectional view schematically illustrating the resonatorelement according to the embodiment.

FIG. 5 is a perspective view schematically illustrating an AT-cut quartzcrystal substrate.

FIG. 6 is a sectional view schematically illustrating the resonatorelement according to the embodiment.

FIG. 7 is a plan view schematically illustrating the resonator elementaccording to the embodiment.

FIG. 8 is a sectional view schematically illustrating the resonatorelement according to the embodiment.

FIG. 9 is a sectional view schematically illustrating the resonatorelement according to the embodiment.

FIG. 10 is a sectional view schematically illustrating a process ofmanufacturing the resonator element according to the embodiment.

FIG. 11 is a plan view schematically illustrating the resonator elementaccording to a modification example of the embodiment.

FIG. 12 is a graph illustrating a CI value of the resonator elementaccording to an experimental example.

FIG. 13 is a plan view schematically illustrating a resonator accordingto the embodiment.

FIG. 14 is a sectional view schematically illustrating the resonatoraccording to the embodiment.

FIG. 15 is a sectional view schematically illustrating a resonatordevice according to the embodiment.

FIG. 16 is a sectional view schematically illustrating a resonatordevice according to a first modification example of the embodiment.

FIG. 17 is a sectional view schematically illustrating a resonatordevice according to a second modification example of the embodiment.

FIG. 18 is a sectional view schematically illustrating an oscillatoraccording to the embodiment.

FIG. 19 is a sectional view schematically illustrating an oscillatoraccording to a modification example of the embodiment.

FIG. 20 is a plan view schematically illustrating an electronicapparatus according to the embodiment.

FIG. 21 is a perspective view schematically illustrating an electronicapparatus according to the embodiment.

FIG. 22 is a perspective view schematically illustrating an electronicapparatus according to the embodiment.

FIG. 23 is a perspective view schematically illustrating an electronicapparatus according to the embodiment.

FIG. 24 is a plan view schematically illustrating a moving objectaccording to the embodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, preferred embodiments of the invention will be described indetail with reference to the drawings. The embodiments to be describedbelow do not inappropriately limit content of the invention described inthe appended claims. All of the configurations to be described below maynot be said to be indispensable configuration prerequisites.

1. Resonator Element

First, a resonator element according to an embodiment will be describedwith reference to the drawings. FIG. 1 is a perspective viewschematically illustrating a resonator element 100 according to theembodiment. FIG. 2 is a plan view schematically illustrating theresonator element 100 according to the embodiment. FIG. 3 is a sectionalview taken along the line III-III of FIG. 2 schematically illustratingthe resonator element 100 according to the embodiment. FIG. 4 is asectional view taken along the line IV-IV of FIG. 2 schematicallyillustrating the resonator element 100 according to the embodiment.

As illustrated in FIGS. 1 to 4, the resonator element 100 includes aquartz crystal substrate 10 and excitation electrodes 20 a and 20 b.

The quartz crystal substrate 10 is configured as an AT-cut quartzcrystal substrate. Here, FIG. 5 is a perspective view schematicallyillustrating an AT-cut quartz crystal substrate 101.

A piezoelectric material such as quartz crystal is generally a trigonalsystem and has quartz crystal axes (X, Y, and Z), as illustrated in FIG.5. The X axis is an electric axis, the Y axis is a mechanical axis, andthe Z axis is an optical axis. The quartz crystal substrate 101 is aflat substrate which is a so-called rotational Y-cut quartz crystalsubstrate cut out from a piezoelectric material (for example, asynthetic crystal) along a fat plane rotated from the XZ plane (which isa plane including the X and Z axes) by an angle θ around the X axis. TheY and Z axes are also rotated by θ around the X axis to form Y′ and Z′axes, respectively. The quartz crystal substrate 101 is a substrate thathas a plane including the X and Z′ axes as a main plane and has athickness in the direction oriented along the Y′ axis. Here, whenθ=35°15′ is set, the quartz crystal substrate 101 is an AT-cut quartzcrystal substrate. Accordingly, in the AT-cut quartz crystal substrate101, an XZ′ plane (which is a plane including the X and Z′ axes)perpendicular to the Y′ axis is a main plane (a main plane of avibration section) and thickness shear vibration can be realized as mainvibration. The quartz crystal substrate 10 can be obtained by processingthe AT-cut quartz crystal substrate 101.

As illustrated in FIG. 5, the quartz crystal substrate 10 is configuredas an AT-cut quartz crystal substrate in which the X axis of theorthogonal coordinate system having the X axis serving as an electricaxis, the Y axis serving as a mechanical axis, and the Z axis serving asan optical axis, which are crystallographic axes of quartz crystal, isset as a rotation axis, an axis inclined from the Z axis so that the +Zside is rotated in the −Y direction of the Y axis is set as a Z′ axis,an axis inclined from the Y axis so that the +Y side is rotated in the+Z direction of the Z axis is set as a Y′ axis, a plane including the Xand Z′ axes is set as a main plane, and the direction oriented along theY′ axis is set as a thickness direction. In FIGS. 1 to 4 and FIGS. 6 to11 to be described below, the X, Y′, and Z′ axes orthogonal to eachother are illustrated.

For example, as illustrated in FIG. 2, the quartz crystal substrate 10has a rectangular shape in which a direction (Y′ axis direction)oriented along the Y′ axis is set as a thickness direction, a direction(X axis direction) oriented in the X axis is set as a long side in aplan view from the Y′ axis direction (hereinafter simply referred to asthe “plan view”), and a direction (Z′ axis direction) oriented along theZ′ axis is set as a short side. The quartz crystal substrate 10 includesa peripheral section (second region) 12 and a vibration section (firstregion) 14.

As illustrated in FIG. 2, the peripheral section 12 is formed in theperiphery of the vibration section 14. The peripheral section 12 isformed along the outer frame of the vibration section 14. The peripheralsection 12 has a thickness thinner than the vibration section 14 (thethickness is thinner than that of the vibration section 14).

As illustrated in FIG. 2, in the plan view, the vibration section 14 issurrounded by the peripheral section 12 and has a thickness thicker thanthe peripheral section 12. The vibration section 14 has a side orientedalong the X axis and a side oriented along the Z′ axis. Specifically,the vibration section 14 has a rectangular shape in which a long side isformed in the X axis direction and a short side is formed in the Z′ axisdirection in the plan view. The vibration section 14 includes a firstportion 15 and a second portion 16.

The first portion 15 of the vibration section 14 has a thickness thickerthan the second portion 16. In an example illustrated in FIGS. 3 and 4,the first portion 15 is a portion that has a thickness t1. The firstportion 15 has a quadrangular shape in the plan view.

The second portion 16 of the vibration section 14 has a thicknessthinner than the first portion 15. In the illustrated example, thesecond portion 16 is a portion that has a thickness t2. The secondportion 16 is formed in the +X direction of the X axis (+X axisdirection) and the −X direction of the X axis (−X axis direction) of thefirst portion 15. That is, the first portion 15 is interposed betweenthe second portions 16 in the X axis direction. As described above, thevibration section 14 includes two types of portions 15 and 16 havingdifferent thicknesses. Thus, the resonator element 100 can be said tohave a two-stage mesa structure.

The vibration section 14 can vibrate so that thickness shear vibrationis main vibration. Since the vibration section 14 has the two-stage mesastructure, the resonator element 100 can have an energy trapped effect.The “thickness shear vibration” refers to vibration in which adisplacement direction of a quartz crystal substrate is parallel to amain plane of the quartz crystal substrate (in the illustrated example,the displacement direction of the quartz crystal substrate is the X axisdirection) and a wave propagation direction is the thickness directionof the quartz crystal substrate.

As illustrated in FIGS. 3 and 4, the vibration section 14 includes afirst projection portion 17 projecting from the peripheral section 12 inthe +Y′ direction of the Y′ axis (+Y′ axis direction) and a secondprojection portion 18 projecting from the peripheral section 12 in the−Y′ direction of the Y′ axis (−Y′ axis direction). For example, theprojection portions 17 and 18 have the same shape. The projectionportions 17 and 18 have the same size.

On a side surface 17 a of the first projection portion 17 in the +X axisdirection and a side surface 17 b of the first projection portion 17 inthe −X axis direction and on a side surface 18 a of the secondprojection portion 18 in the +X axis direction and a side surface 18 bof the second projection portion 18 in the −X axis direction, asillustrated in FIG. 4, for example, two step differences are formed dueto a difference between the thickness of the first portion 15 and thethickness of the second portion 16 or a difference between the thicknessof the second portion 16 and the thickness of the peripheral section 12.

A side surface 17 c of the first projection portion 17 in the +Z′direction of the Z′ axis (the +Z′ axis direction) is, for example, avertical surface to a plane including the X axis and the Z′ axis, asillustrated in FIG. 3. Aside surface 17 d of the first projectionportion 17 in the −Z′ direction of the Z′ axis (the −Z′ axis direction)is, for example, a surface inclined with respect to the plane includingthe X axis and the Z′ axis.

A side surface 18 c of the second projection portion 18 in the +Z′ axisdirection is, for example, a surface inclined with respect to the planeincluding the X axis and the Z′ axis, as illustrated in FIG. 3. A sidesurface 18 d of the second projection portion 18 in the −Z′ axisdirection is a plane vertical to the plane including the X axis and theZ′ axis.

The side surface 17 d of the first projection portion 17 and the sidesurface 18 c of the second projection portion 18 are formed as inclinedsurfaces with respect to the plane including the X axis and the Z′ axis,for example, when an m surface of quartz crystal is exposed byperforming an etching process on the AT-cut quartz crystal substrateusing a solution containing a hydrofluoric acid as an etchant. Althoughnot illustrated, other side surfaces of the quartz crystal substrate 10in the −Z′ direction other than the side surfaces 17 d and 18 c may alsobe formed as inclined surfaces with respect to the plane including the Xaxis and the Z′ axis by exposing the m surface of the quartz crystal.

As illustrated in FIG. 6, the side surfaces 17 d and 18 c may bevertical surfaces to the plane including the X axis and the Z′ axis. Forexample, by processing the AT-cut quartz crystal substrate by a laser oretching AT-cut quartz crystal substrate by dry etching, the sidesurfaces 17 d and 18 c can be formed as vertical surfaces to the planeincluding the X axis and the Z′ axis. For convenience, FIG. 1illustrates the side surfaces 17 d and 18 c which are the verticalsurfaces to the plane including the X axis and the Z′ axis.

In the resonator element 100, as illustrated in FIG. 2, when Sz is thelength of the side surfaces 17 d and 18 c along the Z′ axis and Mz isthe length of the vibration section 14 along the Z′ axis in the planview, for example, formula (1) below is satisfied. Here, Mz is the sizeof a flat portion (specifically, the plane including the X axis and theZ′ axis) of the vibration section 14 in the Z′ axis direction.0≦Sz/Mz≦0.05  (1)

When Sz/Mz=0, as illustrated in FIG. 6, the side surfaces 17 d and 18 care vertical to the plane including the X axis and the Z′ axis.

The first excitation electrode 20 a and the second excitation electrode20 b are formed to overlap each other in the plan view of the vibrationsection 14. In the illustrated example, the excitation electrodes 20 aand 20 b are also formed in the peripheral section 12. For example, theshapes of the excitation electrodes 20 a and 20 b in the plan view (theshapes when viewed in the Y′ axis direction) are rectangular. Thevibration section 14 is formed inside the outer frames of the excitationelectrodes 20 a and 20 b in the plan view. That is, the areas of theexcitation electrodes 20 a and 20 b are greater than the area of thevibration section 14 in the plan view. The excitation electrodes 20 aand 20 b are electrodes that apply a voltage to the vibration section14.

The first excitation electrode 20 a is connected to the first electrodepad 24 a via a first extraction electrode 22 a. The second excitationelectrode 20 b is connected to the second electrode pad 24 b via asecond extraction electrode 22 b. For example, the electrode pads 24 aand 24 b are electrically connected to an IC chip (not illustrated) thatdrives the resonator element 100. The electrode pads 24 a and 24 b areformed on the side of the peripheral section 12 in the +X axisdirection. The excitation electrodes 20 a and 20 b, the extractionelectrodes 22 a and 22 b, and the electrode pads 24 a and 24 b areformed, for example, by stacking chromium and gold in this order fromthe side of the quartz crystal substrate 10.

The quartz crystal substrate 10 includes second protrusions 30 a, 30 b,30 c, and 30 d and first protrusions 40 a and 40 b.

As illustrated in FIGS. 1 and 2, the second protrusions 30 a and 30 bare formed to be lined on both sides of a middle region of theperipheral section 12, that is, in the direction oriented along the Z′axis, on a free end side of the peripheral section 12 (the other endside of the peripheral section 12 in the direction oriented along the Xaxis). Here, the resonator element 100 is fixed to another member (forexample, a package) in the electrode pads 24 a and 24 b. Accordingly, inthe resonator element 100, the side of the electrode pads 24 a and 24 bof the peripheral section 12 (the side in the +X axis direction in theillustrated example) is a mounting side (fixing end side and one endside of the peripheral section 12 in the direction oriented along the Xaxis) and the opposite side (the side in the −X axis direction in theillustrated example) is the free end side. In the example illustrated inFIG. 2, the second protrusions 30 a and 30 b are disposed on both sidesof the middle region of the peripheral section 12 (for example, bothsides of an imaginary straight line α parallel to the X axis passingthrough the center of the quartz crystal substrate 10 in the plan view)on the side of the peripheral section 12 in the −X axis direction. Thesecond protrusions 30 a and 30 b are formed on the surface of theperipheral section 12 in the +Y′ axis direction.

The second protrusions 30 c and 30 d are formed on the surface of theperipheral section 12 in the −Y′ axis direction, as illustrated in FIG.4. In the plan view, the second protrusion 30 c is formed to overlap thesecond protrusion 30 a and the second protrusion 30 d is formed tooverlap the second protrusion 30 b.

For example, the shapes of the second protrusions 30 a, 30 b, 30 c, and30 d are rectangular parallelepipeds. For example, the thicknesses ofthe second protrusions 30 a, 30 b, 30 c, and 30 d are the same as thethicknesses of the projection portions 17 and 18.

As illustrated in FIGS. 1 and 2, the first protrusion 40 a is formedbetween one pair of electrode pads 24 a and 24 b formed on the mountingside of the peripheral section 12. In the example illustrated in FIG. 2,the first protrusion 40 a is formed in the +X axis direction from animaginary straight line β connecting the center of the first electrodepad 24 a to the center of the second electrode pad 24 b in the planview. The first protrusion 40 a is disposed in a row with the vibrationsection 14 in a displacement direction (the X axis direction in theillustrated example) of the thickness shear vibration of the vibrationsection 14. The first protrusion 40 a is formed on the surface of theperipheral section 12 in the +Y′ axis direction.

The first protrusion 40 b is formed on the surface of the peripheralsection 12 in the −Y′ axis direction. In the plan view, the firstprotrusion 40 b is formed to overlap the first protrusion 40 a.

For example, the shapes of the first protrusions 40 a and 40 b arerectangular parallelepipeds that have side surfaces 4 and 5 extendingalong the Z′ axis. In the illustrated example, the side surface 4 is asurface oriented in the +X axis direction and the side surface 5 is asurface oriented in the −X axis direction. For example, the thicknessesof the first protrusions 40 a and 40 b are the same as the thicknessesof the first protrusions 30 a, 30 b, 30 c, and 30 d.

Here, FIG. 7 is a schematic diagram in which isodynamic lines connectingpoints at which vibration displacement energy (a product of a square ofvibration displacement and amass at that position) generated at the timeof excitation of the resonator element 100 overlap with a plan viewschematically illustrating the resonator element 100 by one-dot chainlines. That is, the one-dot chain lines illustrated in FIG. 7 show adistribution of the vibration displacement energy. As illustrated inFIG. 7, the first protrusions 40 a and 40 b are disposed in regionswhich the vibration displacement energy of the thickness shear vibrationby the vibration section 14 does not reach. That is, at the positions atwhich the first protrusions 40 a and 40 b are formed, the vibrationdisplacement energy of the thickness shear vibration by the vibrationsection 14 is zero. A distance D between the first protrusions 40 a and40 b and the vibration section 14 is, for example, equal to or greaterthan 200 μm and equal to or less than 300 μm.

In the resonator element 100, when Lx is the length (the length alongthe X axis) of the first protrusions 40 a and 40 b in the displacementdirection of the thickness shear vibration of the first protrusions 40 aand 40 b and λ is a wavelength of flexural vibration generated in thequartz crystal substrate 10, a relation of formula (2) below issatisfied.“λ/2×(2n+1)−0.1λ≦Lx≦λ/2×(2n+1)+0.1λ(where n is a positive integer)  (2)

The “wavelength of the flexural vibration generated in the quartzcrystal substrate 10” is a wavelength of flexural vibration which isspurious (unnecessary vibration) generated in the quartz crystalsubstrate 10. For example, the wavelength λ of the flexural vibrationcan be obtained by a mathematical formula such as “λ/2=(1.332/f)−0.0024”where a resonance frequency of the resonator element 100 is f.

In formula (2), “−0.1λ” and “+0.1λ” indicate a variation (manufacturingvariation) in the dimensions. The influence on the resonator element 100can be set to be sufficiently small in the manufacturing variation.Specifically, the flexural vibration can be reduced to be sufficientlysmall in the manufacturing variation.

By satisfying formula (2), as illustrated in FIG. 8, the side surfaces 4and 5 of the first protrusions 40 a and 40 b can be formed to matchpositions of the maximum amplitude (a peak M or a trough V) of theflexural vibration generated in the quartz crystal substrate 10. In theexample illustrated in FIG. 8, the side surface 4 is disposed at thepeak M of the flexural vibration generated in the quartz crystalsubstrate 10 and the side surface 5 is disposed at the trough V of theflexural vibration generated in the quartz crystal substrate 10.Specifically, the side surfaces 4 and 5 are formed such that a parallelto the Y′ axis passing through the maximum amplitude point (the peak Mor the trough V) of the wavelength W of the flexural vibration generatedin the quartz crystal substrate 10 matches an imaginary straight line γ.Although not illustrated, the side surface 4 may be disposed at thetrough V of the flexural vibration and the side surface 5 may bedisposed at the peak M of the flexural vibration. FIG. 8 is a schematicdiagram in which the amplitude of the flexural vibration generated inthe quartz crystal substrate 10 overlaps with a plan view schematicallyillustrating the resonator element 100.

In the example illustrated in FIG. 8, a Y′Z′ plane (which is a planeincluding the Y′ axis and the Z′ axis) including the side surfaces 17 aand 17 b of the first projection portion 17, a Y′Z′ plane including theside surfaces 18 a and 18 b of the second projection portion 18, and endsurfaces 21 a and 21 b of the excitation electrodes 20 a and 20 b areformed to also match the positions of the maximum amplitude of theflexural vibration generated in the quartz crystal substrate 10.

For example, when the quartz crystal substrate is processed by wetetching, as illustrated in FIG. 9, the side surfaces 4 and 5 of thefirst protrusions 40 a are inclined with respect to the surface of theperipheral section 12 in the +Y′ axis direction by etching anisotropy.In this case, the length Lx is a center distance between the twoinclined side surfaces, as illustrated in FIG. 9. This is not limited tothe length of the first protrusion 40 a, but the same applies for thelength (for example, Mz or Lz) of each portion of the quartz crystalsubstrate 10 included in the resonator element according to theinvention. In this case, “the side surfaces 4 and 5 of the firstprotrusion 40 a are formed to match the positions of the maximumamplitude of the flexural vibration generated in the quartz crystalsubstrate 10” means that the centers of the inclined side surfaces 4 and5 are formed to match the positions of the maximum amplitude of theflexural vibration generated in the quartz crystal substrate 10, asillustrated in FIG. 9.

In the resonator element 100, as illustrated in FIG. 2, when Lz is thelength of the first protrusions 40 a and 40 b along the Z′ axis and Mzis the length of the vibration section 14 along the Z′ axis, formula (3)below is preferably satisfied.0<Lz/Mz≦0.7  (3)

By satisfying formula (3), it is possible to reduce equivalent seriesresistance (which will be described below in detail in “ExperimentalExample”). Specifically, Lz is about 0.07 mm.

In a method of manufacturing the resonator element 100, for example, thequartz crystal substrate 10 is formed by photolithography and etching.The etching may be dry etching or wet etching. The protrusions 30 a, 30b, 30 c, 30 d, 40 a, and 40 b may be formed simultaneously with thevibration section 14. The excitation electrodes 20 a and 20 b, theextraction electrodes 22 a and 22 b, and the electrode pads 24 a and 24b (hereinafter also referred to as “the excitation electrodes 20 a and20 b and the like”) are formed, for example, by forming conductor layers(not illustrated) by a sputtering method or a vacuum evaporation methodand patterning the conductor layers by photolithography and etching.

The method of manufacturing the resonator element 100 includes acleaning step of cleaning the resonator element 100 after the excitationelectrodes 20 a and 20 b and the like are formed. For example, asillustrated in FIG. 10, the cleaning step is performed by accommodatingthe resonator element 100 in a jig 50 and flowing water (for example,pure water) from an opening 52 formed in the jig 50. The resonatorelement 100 is accommodated in the jig 50 without contact of theperipheral section 12, the vibration section 14, and the excitationelectrodes 20 a and 20 b with the jig 50 by the protrusions 30 c, 30 d,and 40 b. In the cleaning step, foreign matters attached to theresonator element 100 can be removed. The cleaning step may also beperformed before the excitation electrodes 20 a and 20 b and the likeare formed and after the quartz crystal substrate 10 is formed.

The resonator element 100 has, for example, the followingcharacteristics.

The resonator element 100 includes the first protrusions 40 a and 40 bformed between the one pair of electrode pads 24 a and 24 b. Since theelectrode pads 24 a and 24 b are formed to include edges (corners) ofthe peripheral section 12 in the +X axis direction, the distance betweenthe first protrusions 40 a and 40 b and the vibration section 14 can belengthened by forming the first protrusions 40 a and 40 b between theelectrode pads 24 a and 24 b more than when the first protrusions arenot formed between the electrode pads. Therefore, the first protrusions40 a and 40 b can be disposed in the regions which the vibrationdisplacement energy of the thickness shear vibration by the vibrationsection 14 does not reach. Accordingly, in the resonator element 100, itis possible to reduce the influence of the first protrusions 40 a and 40b on the vibration of the vibration section 14. As a result, it ispossible to reduce deterioration in electric characteristics.

The resonator element 100 further includes the second protrusions 30 a,30 b, 30 c, and 30 d formed on the free end side of the peripheralsection 12. Therefore, in the cleaning step of cleaning the resonatorelement 100, the resonator element 100 can be accommodated in the jig 50without contact of the vibration section 14 or the excitation electrodes20 a and 20 b to the jig 50. For example, when the first protrusions arenot formed between the electrode pads, a distance between the firstprotrusions and the opening formed in the jig is close. Thus, when theresonator element is moved with respect to the jig during the cleaning,the first protrusions fall to the opening in some cases. Furthermore,for example, when the second protrusions 30 a, 30 b, 30 c, and 30 d ofthe resonator element 100 come into contact with a package (a packageaccommodating the resonator element 100), it is possible to prevent thevibration section 14 or the excitation electrodes 20 a and 20 b fromcolliding against the package and damaging. As a result, the resonatorelement 100 can have, for example, high reliability.

The resonator element 100 satisfies formula (2). Therefore, in theresonator element 100, one side of the side surfaces 4 and 5 can bedisposed at the peak of the flexural vibration and the other side of theside surfaces 4 and 5 can be disposed at the trough of the flexuralvibration. Accordingly, in the resonator element 100, it is possible toattenuate the thickness shear vibration in the peripheral section 12while reducing the flexural vibration, and thus it is possible toefficiently trap the vibration displacement energy of the thicknessshear vibration.

The example has been described above in which the areas of theexcitation electrodes 20 a and 20 b are greater than the area of thevibration section 14 in the plan view. However, in the resonator elementaccording to the invention, the areas of the excitation electrodes 20 aand 20 b may be less than the area of the vibration section 14 in theplan view. In this case, the excitation electrodes 20 a and 20 b areformed inside the outer frame of the vibration section 14 in the planview.

The two-stage mesa structure in which the vibration section 14 has thetwo types of portions 15 and 16 having different thicknesses has beendescribed above. However, the number of stages of the mesa structure ofthe resonator element according to the invention is not particularlylimited. For example, the resonator element according to the inventionmay have a three-stage mesa structure in which the vibration sectionincludes three types of portions having different thicknesses or mayhave a one-stage mesa structure in which the vibration section has noportion with a different thickness.

The example has been described above in which a step difference is notformed by a difference between the thickness of the first portion 15 andthe thickness of the second portion 16 in the side surfaces 17 c and 17d of the first projection portion 17 and the side surfaces 18 c and 18 dof the second projection portion 18. However, in the resonator elementaccording to the invention, a step difference (a step difference betweenthe thickness of the first portion 15 and the thickness of the secondportion 16) may be formed in the side surfaces 17 c, 17 d, 18 c, and 18d.

The example has been described above in which the resonator elementincludes the first projection portion 17 projecting from the peripheralsection 12 in the +Y′ axis direction and the second projection portion18 projecting from the peripheral section 12 in the −Y′ axis direction.However, the resonator element according to the invention may includeonly one of the projection portions.

The example in which the vibration section 14 has the rectangular shapein the plan view has been described above. However, the vibrationsection of the resonator element according to the invention may bechamfered edges (corners) in the plan view. That is, the vibrationsection may have the rectangular shape with cut-out corners.

The example in which the quartz crystal substrate 10 is the AT-cutquartz crystal substrate has been described above. However, in theresonator element according to the invention, the quartz crystalsubstrate is not limited to the AT-cut quartz crystal substrate, but maybe a piezoelectric substrate in which thickness shear vibration isgenerated, such as an SC-cut quartz crystal substrate or a BT-cut quartzcrystal substrate.

2. Modification Examples of Resonator Element

Next, a resonator element according to a modification example of theinvention will be described with reference to the drawings. FIG. 11 is aplan view schematically illustrating a resonator element 200 accordingto the modification example of the embodiment. Hereinafter, in theresonator element 200 according to the modification example of theembodiment, the same reference numerals are given to elements having thesame functions as the constituent elements of the resonator element 100according to the embodiment and the detailed description thereof will beomitted.

In the above-described resonator element 100, as illustrated in FIG. 2,the quartz crystal substrate 10 has a rectangular shape in the planview. Accordingly, in the resonator element 200, as illustrated in FIG.11, edges (corners) of the quartz crystal substrate 10 in the −X axisdirection are chamfered. In other words, the resonator element has ashape in which the rectangular corners are cut out. For example, edges(corners) of the quartz crystal substrate 10 in the +X axis directionmay also be chamfered.

In the resonator element 200, the edges of the quartz crystal substrate10 are chamfered. Therefore, when the quartz crystal substrate 10 isformed by etching, it is possible to reduce generation of burr (forexample, etching residue). Further, when the resonator element 200 ismounted on a package, it is possible to reduce a possibility of thecorners of the quartz crystal substrate 10 coming into contact with thepackage and damaging.

3. Experimental Example

Hereinafter, the invention will be described more specifically accordingto an experimental example. The invention is not limited to thefollowing experimental example.

In the experimental example, the same resonator element as theabove-described resonator element 200 was manufactured. Specifically,the resonator element in which the length of the quartz crystalsubstrate 10 along the X axis was about 1 mm, the length of the quartzcrystal substrate 10 along the Z′ axis was about 0.6 mm, and theresonance frequency was about 26 MHz was manufactured. In the resonatorelement, a CI value was measured by changing the length Lz of the firstprotrusions 40 a and 40 b along the Z′ axis and the length Mz of thevibration section 14 along the Z′ axis. The dimensions Lz and Mz weremeasured by a dimension measurement device and the CI value was measuredusing a network analyzer.

FIG. 12 is a graph illustrating a relation between a ratio (Lz/Mz) of Lzto Mz and the CI value. As illustrated in FIG. 12, by satisfying therelation of “0<Lz/Mz≦0.7”, it can be understood that the CI value can besuppressed to a value less than 70Ω. By satisfying a relation of“0.1≦Lz/Mz≦0.6”, it can be understood that the CI value can besuppressed to a value less than 65Ω. By satisfying a relation of“0.2≦Lz/Mz≦0.5”, it can be understood that the CI value can besuppressed to smaller values less than 65Ω. By satisfying a relation of“0.3≦Lz/Mz≦0.4”, it can be understood that the CI value can besuppressed to a value less than 60Ω.

4. Resonator

Next, a resonator according to the embodiment will be described withreference to the drawings. FIG. 13 is a plan view schematicallyillustrating a resonator 700 according to the embodiment. FIG. 14 is asectional view taken along the line XIV-XIV of FIG. 13 schematicallyillustrating the resonator 700 according to the embodiment. Forconvenience, a seal ring 713 and a lid 714 are not illustrated in FIG.13.

The resonator 700 includes a resonator element according to theinvention. Hereinafter, the resonator 700 including the resonatorelement 100 as the resonator element according to the invention will bedescribed. As illustrated in FIGS. 13 and 14, the resonator 700 includesthe resonator element 100 and a package 710.

The package 710 includes a box-shaped base 712 that has a concaveportion 711 of which the top surface is opened and a plate-shaped lid714 that is joined to the base 712 to close the opening of the concaveportion 711. The package 710 has an accommodation space formed so thatthe concave portion 711 is closed with the lid 714, and thus theresonator element 100 is accommodated to be installed in theaccommodation space so that the resonator element 100 is airtight. Thatis, the resonator element 100 is accommodated in the package 710.

For example, the accommodation space (the concave portion 711) in whichthe resonator element 100 is accommodated may be in a depressurizedstate (preferably, a vacuum state) or an inert gas such as nitrogen,helium, or argon may be enclosed. Accordingly, the vibrationcharacteristics of the resonator element 100 are improved.

As the material of the base 712, for example, any of various ceramicssuch as aluminum oxide can be used. As the material of the lid 714, forexample, a material with a close linear expansion coefficient to thematerial of the base 712 can be used. Specifically, when the material ofthe base 712 is a ceramic, the material of the lid 714 is an alloy suchas Kovar.

The bonding of the base 712 and the lid 714 is performed by forming theseal ring 713 on the base 712, mounting the lid 714 on the seal ring713, and welding the seal ring 713 to the base 712 using, for example, aresistance welder. The bonding of the base 712 and the lid 714 is notparticularly limited, but may be performed using an adhesive or may beperformed by seam welding.

A pillow portion 720 is formed on the bottom surface of the concaveportion 711 of the package 710. For example, the pillow portion 720 isformed to come into contact with the second protrusions 30 c and 30 d ofthe resonator element 100. For example, the material of the pillowportion 720 is the same as the material of the base 712. The pillowportion 720 may be integrated with the base 712. For example, even whenan impact is applied to the resonator 700 from the outside, the pillowportion 720 and the second protrusions 30 c and 30 d come into contactwith each other, and thus it is possible to prevent the vibrationsection 14 of the resonator element 100 from colliding against theconcave portion 711 of the package 710 and damaging. Further, forexample, before the vibration section 14 collides against the lid 714,the second protrusions 30 c and 30 d collide against the lid 714.Therefore, it is possible to prevent the vibration section 14 fromdamaging.

A first connection terminal 730 and a second connection terminal 732 areformed on the bottom surface of the concave portion 711 of the package710. The first connection terminal 730 is formed to face the firstelectrode pad 24 a of the resonator element 100. The second connectionterminal 732 is formed to face the second electrode pad 24 b of theresonator element 100. The connection terminals 730 and 732 areelectrically connected to the electrode pads 24 a and 24 b via aconductive fixing member 734, respectively.

A first external terminal 740 and a second external terminal 742 areformed on the bottom surface (the bottom surface of the base 712) of thepackage 710. For example, the first external terminal 740 is formed at aposition overlapping the first connection terminal 730 in the plan view.For example, the second external terminal 742 is formed at a positionoverlapping the second connection terminal 732 in the plan view. Thefirst external terminal 740 is electrically connected to the firstconnection terminal 730 through a via (not illustrated). The secondexternal terminal 742 is electrically connected to the second connectionterminal 732 through a via (not illustrated).

As the connection terminals 730 and 732 and the external terminals 740and 742, for example, metal coating films formed by stacking coatingfilms of Ni (nickel), Au (gold), Ag (silver), Cu (copper), or the likeon metalized layers (underlying layers) of Cr (chromium), W (tungsten),or the like are used. As the conductive fixing member 734, for example,a solder, a silver paste, a conductive adhesive (an adhesive in whichconductive fillers such as metal particles are dispersed in a resinmaterial), or the like is used.

Since the resonator 700 includes the resonator element 100, it ispossible to reduce deterioration in the electric characteristics.

5. Resonator Device

Next, a resonator device according to the embodiment will be describedwith reference to the drawings. FIG. 15 is a sectional viewschematically illustrating a resonator device 800 according to theembodiment.

Hereinafter, in the resonator device 800 according to the embodiment,the same reference numerals are given to elements having the samefunctions as the constituent elements of the above-described resonator700 according to the embodiment and the detailed description thereofwill be omitted.

The resonator device 800 includes the resonator element according to theinvention. Hereinafter, a resonator device 800 including the resonatorelement 100 as the resonator element according to the invention will bedescribed. The resonator device 800 includes the resonator element 100,the package 710, and a thermosensitive element (electronic element) 810,as illustrated in FIG. 15.

The package 710 includes an accommodation portion 812 that accommodatesthe thermosensitive element 810. For example, the accommodation portion812 can be formed by forming a frame-shaped member 814 on the bottomsurface of the base 712.

The thermosensitive element 810 is, for example, a thermistor in which aphysical quantity, for example, electric resistance, is changedaccording to a change in temperature. The electric resistance of thethermistor can be detected by an external circuit to measure detectiontemperature of the thermistor.

Another electric component may be accommodated in the accommodationspace (the concave portion 711) of the package 710. As the electriccomponent, an IC chip or the like controlling driving of the resonatorelement 100 can be exemplified.

Since the resonator device 800 includes the resonator element 100, it ispossible to reduce the deterioration in the electric characteristics.

6. Modification Examples of Resonator Device

6.1. First Modification Example

Next, a resonator device according to a first modification example ofthe embodiment will be described with reference to the drawing. FIG. 16is a sectional view schematically illustrating a resonator device 900according to the first modification example of the embodiment.

Hereinafter, in the resonator device 900 according to the firstmodification example of the embodiment, the same reference numerals aregiven to elements having the same functions as the constituent elementsof the above-described resonator device 800 according to the embodimentand the detailed description thereof will be omitted.

In the above-described resonator device 800, as illustrated in FIG. 15,the accommodation portion 812 that accommodates a thermosensitiveelement 810 is formed by forming a frame-shaped member 814 on the bottomsurface of the base 712.

On the other hand, in the resonator device 900, as illustrated in FIG.16, the thermosensitive element 810 is accommodated in a concave portion912 by forming the concave portion 912 on the bottom surface (the bottomsurface of the base 712) of the package 710. In the illustrated example,a third connection terminal 930 is formed on the bottom surface of theconcave portion 912 and the thermosensitive element 810 is formed undera third connection terminal 930 via a metal bump or the like. In theillustrated example, the third connection terminal 930 is connected to awiring 932 formed in the base 712. The third connection terminal 930 iselectrically connected to the first external terminal 740 and the firstconnection terminal 730 by the wiring 932. For example, the material ofthe third connection terminal 930 is the same as the material of theconnection terminal 730 or 732. The material of the wiring 932 is notparticularly limited as long as the material is conductive.

Since the resonator device 900 includes the resonator element 100, it ispossible to reduce the deterioration in the electric characteristics.

6.2. Second Modification Example

Next, a resonator device according to a modification example of theembodiment will be described with reference to the drawing. FIG. 17 is asectional view schematically illustrating a resonator device 1000according to a second modification example of the embodiment.

Hereinafter, in the resonator device 1000 according to the secondmodification example of the embodiment, the same reference numerals aregiven to elements having the same functions as the constituent elementsof the above-described resonator devices 800 and 900 according to theembodiment and the detailed description thereof will be omitted.

In the resonator device 800, as illustrated in FIG. 15, theaccommodation portion 812 that accommodates the thermosensitive element810 is formed for the thermosensitive element 810 by forming theframe-shaped member 814 on the bottom surface side of the base 712.

On the other hand, in the resonator device 1000, as illustrated in FIG.17, the concave portion 912 is formed on the bottom surface (uppersurface of the base 712) of the concave portion 711 and thethermosensitive element 810 is accommodated in the concave portion 912.The thermosensitive element 810 is formed on the third connectionterminal 930.

Since the resonator device 1000 includes the resonator element 100, itis possible to reduce the deterioration in the electric characteristics.

7. Oscillator

Next, an oscillator according to the embodiment will be described withreference to the drawing. FIG. 18 is a sectional view schematicallyillustrating an oscillator 1100 according to the embodiment.

Hereinafter, in the oscillator 1100 according to the embodiment, thesame reference numerals are given to elements having the same functionsas the constituent elements of the above-described resonator 700according to the embodiment and the detailed description thereof will beomitted.

The oscillator 1100 includes the resonator element according to theinvention. Hereinafter, the oscillator 1100 including the resonatorelement 100 as the resonator element according to the invention will bedescribed. As illustrated in FIG. 18, the oscillator 1100 includes theresonator element 100, the package 710, and an IC chip (chip component)1110.

In the oscillator 1100, the concave portion 711 includes a first concaveportion 711 a formed on the top surface of the base 712, a secondconcave portion 711 b formed in the middle of the bottom surface of thefirst concave portion 711 a, and a third concave portion 711 c formed inthe middle of the bottom surface of the second concave portion 711 b.

The first connection terminal 730 and the second connection terminal 732are formed on the bottom surface of the first concave portion 711 a. TheIC chip 1110 is formed on the bottom surface of the third concaveportion 711 c. The IC chip 1110 includes a driving circuit (oscillationcircuit) that controls driving of the resonator element 100. When theresonator element 100 is driven by the IC chip 1110, vibration of apredetermined frequency can be extracted. The IC chip 1110 overlaps theresonator element 100 in the plan view. As illustrated in FIG. 18, thebottom surface of the first concave portion 711 a may also function asthe pillow portion 720 coming into contact with the second protrusions30 c and 30 d of the resonator element 100.

A plurality of internal terminals 1120 electrically connected to the ICchip 1110 via wires 1112 are formed on the bottom surface of the secondconcave portion 711 b. For example, of the plurality of internalterminals 1120, one internal terminal 1120 is electrically connected tothe first connection terminal 730 via a wiring (not illustrated). Of theplurality of internal terminals 1120, the other internal terminals 1120are electrically connected to the second connection terminal 732 viawirings (not illustrated). Accordingly, the IC chip 1110 is electricallyconnected to the resonator element 100. The internal terminal 1120 maybe electrically connected to the external terminal 740 through a via(not illustrated) formed in the base 712.

Since the oscillator 1100 includes the resonator element 100, it ispossible to reduce the deterioration in the electric characteristics.

8. Modification Example of Oscillator

Next, an oscillator according to a modification example of theembodiment will be described with reference to the drawing. FIG. 19 is asectional view schematically illustrating an oscillator 1200 accordingto a modification example of the embodiment.

Hereinafter, in the oscillator 1200 according to the modificationexample of the embodiment, the same reference numerals are given toelements having the same functions as the constituent elements of theabove-described oscillator 1100 according to the embodiment and thedetailed description thereof will be omitted.

In the above-described oscillator 1100, as illustrated in FIG. 18, theIC chip 1110 overlaps the resonator element 100 in the plan view.

On the other hand, in the oscillator 1200, as illustrated in FIG. 19,the IC chip 1110 does not overlap the resonator element 100 in the planview. The IC chip 1110 is formed on the side of the resonator element100.

In the oscillator 1200, the package 710 is configured to include aplate-shaped base 712 and a convex-shaped lid 714. The lid 714 is sealedhermetically by melting a metalized layer 1210 formed in thecircumference of the base 712. At this time, a sealing step is performedin a vacuum state so that the inside of the oscillator can bevacuumized. As a sealing mechanism, a mechanism melting and welding thelid 714 using a laser beam or the like may be used.

In the illustrated example, the first connection terminal 730 iselectrically connected to the first external terminal 740 through a via1220 formed in the base 712. The internal terminal 1120 is electricallyconnected to the first external terminal 740 through the via 1220 formedin the base 712. The internal terminal 1120 is electrically connected tothe first connection terminal 730 via a wiring (not illustrated). The ICchip 1110 is formed on the internal terminal 1120 via a metal bump orthe like.

Since the oscillator 1200 includes the resonator element 100, it ispossible to reduce the deterioration in the electric characteristics.

9. Electronic Apparatus

Next, electronic apparatuses according to the embodiment will bedescribed with reference to the drawings. An electronic apparatusaccording to the embodiment includes the resonator element according tothe invention. Hereinafter, electronic apparatuses including theresonator element 100 as the resonator element according to theinvention will be described.

FIG. 20 is a plan view schematically illustrating a smartphone 1300 asthe electronic apparatus according to the embodiment. As illustrated inFIG. 20, the smartphone 1300 includes the oscillator 1100 including theresonator element 100.

In the smartphone 1300, the oscillator 1100 is used as, for example, atiming device such as a reference clock oscillation source or the like.The smartphone 1300 can further include a display unit (a liquid crystaldisplay, an organic EL display, or the like) 1310, an operation unit1320, a sound output unit 1330 (microphone or the like). The smartphone1300 may include a touch detection mechanism on the display unit 1310 sothat the display unit 1310 also serves as an operation unit.

An electronic apparatus typified by the smartphone 1300 preferablyincludes an oscillation circuit that drives the resonator element 100and a temperature compensation circuit that corrects a frequencyvariation occurring with a change in the temperature of the resonatorelement 100.

Accordingly, the electronic apparatus typified by the smartphone 1300includes the oscillation circuit that drives the resonator element 100and the temperature compensation circuit that corrects a frequencyvariation occurring with a change in the temperature of the resonatorelement 100, and thus temperature-compensates a resonant frequencyoscillated by the oscillation circuit. Therefore, it is possible toprovide the electronic apparatus with excellent temperaturecharacteristics.

FIG. 21 is a perspective view schematically illustrating a mobile (ornotebook-type) personal computer 1400 as the electronic apparatusaccording to the embodiment. As illustrated in FIG. 21, the personalcomputer 1400 is configured to include a body unit 1404 including akeyboard 1402 and a display unit 1406 including a display unit 1405. Thedisplay unit 1406 is supported to be rotated via a hinge structure unitwith respect to the body unit 1404. In the personal computer 1400, theresonator element 100 functioning as a filter, a resonator, a referenceclock, or the like is built.

FIG. 22 is a perspective view schematically illustrating a mobile phone(also including a PHS) 1500 as the electronic apparatus according to theembodiment. The mobile phone 1500 includes a plurality of operationbuttons 1502, a earpiece 1504, and a mouthpiece 1506. A display unit1508 is disposed between the operation buttons 1502 and the earpiece1504. In the mobile phone 1500, the resonator element 100 functioning asa filter, a resonator, or the like is built.

FIG. 23 is a perspective view schematically illustrating a digital stillcamera 1600 as the electronic apparatus according to the embodiment. InFIG. 23, connection with an external apparatus is also simplyillustrated. Here, a normal camera exposes a silver-salt photo film by alight image of a subject, but the digital still camera 1600 performsphotoelectric conversion on a light image of a subject using an imagesensor such as a charge coupled device (CCD) and generates an imagingsignal (image signal).

A display unit 1603 is formed on the rear surface of a case (body) 1602of the digital still camera 1600 to perform display based on the imagingsignal generated by the CCD. The display unit 1603 functions a finderthat displays a subject as an electronic image. A light-receiving unit1604 including an optical lens (imaging optical system) or a CCD isformed on the front surface (the rear surface side of the drawing) ofthe case 1602.

When a photographer confirms a subject image displayed on the displayunit and presses a shutter button 1606, an imaging signal of the CCD atthat time is transmitted and stored in a memory 1608. In the digitalstill camera 1600, a video signal output terminal 1612 and a datacommunication input/output terminal 1614 are formed on a side surface ofthe case 1602. As illustrated, a television monitor 1630 is connected tothe video signal output terminal 1612 and a personal computer 1640 isconnected to the data communication input/output terminal 1614, asnecessary. The imaging signal stored in the memory 1608 is configured tobe output to the television monitor 1630 or the personal computer 1640through a predetermined operation. In the digital still camera 1600, theresonator element 100 functioning as a filter, a resonator, or the likeis built.

Since the electronic apparatuses 1300, 1400, 1500, and 1600 include theresonator element 100, it is possible to reduce the deterioration in theelectric characteristics.

The electronic apparatus including the resonator element according tothe invention is not limited to the foregoing examples, but may beapplied to, for example, an ink jet ejection apparatus (for example, anink jet printer), a laptop personal computer, a television, a videocamera, a video tape recorder, a car navigation apparatus, a pager, anelectronic organizer (also including a communication function unit), anelectronic dictionary, a calculator, an electronic game apparatus, aword processor, a workstation, a television phone, a security televisionmonitor, electronic binoculars, a POS terminal, medical apparatuses (forexample, an electronic thermometer, a blood pressure meter, ablood-sugar meter, an electrocardiographic apparatus, an ultrasonicdiagnostic apparatus, and an electronic endoscope), a fish finder,various measurement apparatuses, meters (for example, meters forvehicles, airplanes, and ships), and a flight simulator.

10. Moving Object

Next, a moving object according to the embodiment will be described withreference to the drawing. FIG. 24 is a perspective view schematicallyillustrating an automobile as a moving object 1700 according to theembodiment.

The moving object according to the embodiment includes the resonatorelement according to the invention. Hereinafter, a moving objectincluding the resonator element 100 as the resonator element accordingto the invention will be described.

The moving object 1700 according to the embodiment is configured tofurther include a controller 1720 that performs various kinds of controlon an engine system, a brake system, a keyless entry system, and thelike, a controller 1730, a controller 1740, a battery 1750, and a backupbattery 1760. In the moving object 1700 according to the embodiment,some of the constituent elements (each unit) illustrated in FIG. 24 maybe omitted or changed or other constituent elements may be added.

As the moving object 1700, various moving objects can be considered. Forexample, an automobile (also including an electric automobile), anairplane such as a jet plane or a helicopter, a ship, a rocket, and anartificial satellite can be exemplified.

Since the moving object 1700 includes the resonator element 100, it ispossible to reduce the deterioration in the electric characteristics.

The above-described embodiments and modification examples are merelyexamples and the invention is not limited thereto. For example, theembodiments and the modification examples can also be appropriatelycombined.

The invention includes substantially the same configurations (forexample, configurations in which the functions, the methods, and theresults are the same or configurations in which the goals and theadvantages are the same) as the configurations described in theembodiments. The invention includes configurations in which unessentialportions of the configurations described in the embodiments aresubstituted. The invention includes configurations in which the sameoperation and advantages as the configurations described in theembodiments or configurations in which the same goals can be achieved.The invention includes configurations in which known technologies areadded to the configurations described in the embodiments.

The entire disclosure of Japanese Patent Application No. 2015-015325,filed Jan. 29, 2015 is expressly incorporated by reference herein.

What is claimed is:
 1. A resonator element comprising: a quartz crystalsubstrate in which an X axis of an orthogonal coordinate system havingthe X axis serving as an electric axis, a Y axis serving as a mechanicalaxis, and a Z axis serving as an optical axis, which arecrystallographic axes of quartz crystal, is set as a rotation axis, anaxis inclined from the Z axis so that a +Z side is rotated in a −Ydirection of the Y axis is set as a Z′ axis, an axis inclined from the Yaxis so that a +Y side is rotated in a +Z direction of the Z axis is setas a Y′ axis, a plane including the X and Z′ axes is set as a mainplane, and the direction oriented along the Y′ axis is set as athickness direction; and a pair of electrode pads, wherein the quartzcrystal substrate includes a first region in which thickness shearvibration is generated, a second region that is located in periphery ofthe first region and has a thickness thinner than the first region, anda first protrusion that is disposed to be lined with the first region ina direction oriented along the X axis at one end side of the secondregion along the X axis, wherein the one pair of electrode pads aredisposed to be lined in a direction oriented along the Z′ axis at theone end side of the second region in the direction oriented along the Xaxis, wherein the first protrusion is present between the one pair ofelectrode pads, and wherein when Lx is a length of the first protrusionalong the X axis and λ is a wavelength of flexural vibration generatedin the quartz crystal substrate, a relation of“λ/2×(2n+1)−0.1λ≦Lx≦λ/2×(2n+1)+0.1λ” (where n is a positive integer) issatisfied.
 2. The resonator element according to claim 1, wherein whenLz is a length of the first protrusion along the Z′ axis and Mz is alength of the first region along the Z′ axis, a relation of“0<Lz/Mz≦0.7” is satisfied.
 3. The resonator element according to claim1, wherein the first protrusion is disposed in a region which vibrationdisplacement energy by the vibration section does not reach.
 4. Theresonator element according to claim 1, wherein the first protrusion hastwo side surfaces extending along the Z′ axis, and wherein of the twoside surfaces, one side surface is disposed at a position of one maximumamplitude of the flexural vibration and the other side surface isdisposed at a position of the other maximum amplitude of the flexuralvibration.
 5. The resonator element according to claim 1, furthercomprising: a pair of second protrusions that are disposed to be linedin the direction oriented along the Z′ axis at the other end side of thesecond region along the X axis.
 6. The resonator element according toclaim 1, wherein the first region includes a first portion, and a secondportion that has a thickness thinner than the first portion and ispresent between the first portion and the second region at least in avibration direction of the thickness shear vibration in a plan view. 7.The resonator element according to claim 1, further comprising:excitation electrodes that are formed in the first and second regions.8. The resonator element according to claim 2, further comprising:excitation electrodes that are formed in the first and second regions.9. The resonator element according to claim 3, further comprising:excitation electrodes that are formed in the first and second regions.10. The resonator element according to claim 4, further comprising:excitation electrodes that are formed in the first and second regions.11. A resonator comprising: the resonator element according to claim 1;and a package in which the resonator element is accommodated.
 12. Aresonator comprising: the resonator element according to claim 2; and apackage in which the resonator element is accommodated.
 13. A resonatordevice comprising: the resonator element according to claim 1; and anelectronic element.
 14. A resonator device comprising: the resonatorelement according to claim 2; and an electronic element.
 15. Theresonator device according to claim 13, wherein the electronic elementis a thermosensitive element.
 16. An oscillator comprising: theresonator element according to claim 1; and an oscillation circuit thatis electrically connected to the resonator element.
 17. An oscillatorcomprising: the resonator element according to claim 2; and anoscillation circuit that is electrically connected to the resonatorelement.
 18. An electronic apparatus comprising: the resonator elementaccording to claim
 1. 19. A moving object comprising: the resonatorelement according to claim 1.